The inventive concepts relate generally to drive systems for variously transferring input force to output force and, more particularly, to drive systems for manually propelled vehicles such as a bicycle or tricycle or the like, wherein the vehicles are propelled by the rider by rider generated force applied through the legs and feet of the rider.
This application is related to my prior pending U.S. patent applications, Ser. No. 426,917, filed Dec. 20, 1973, for INFINITELY VARIABLE BICYCLE TRANSMISSION, ETC., and Ser. No. 438,728, filed Feb. 1, 1974, for INFINITELY VARIABLE TRANSMISSIONS, ETC., the disclosures of which are specifically incorporated herein by reference and the benefit of the filing dates of which are hereby claimed for common subject matter contained herein.
While cycling has been a universal and common mode of transportation for many decades, the drive systems employed at this time as discussed in U.S. Pat. No. 3,889,974, still basically comprise an annular driving sprocket wheel operated by pedal supporting crank arms, an annular driven rear axle sprocket wheel (one speed) or multiple driven varying size rear axle sprocket wheels, and a closed loop chain operably associated with the sprocket wheels. However, the prior art shows that literally thousands of attempts have been made to provide a variety of other types of drive systems for bicycles and the like. At least as early as the Smith U.S. Pat. No. 596,289 of 1897, it has been recognized that the ability of a bike rider to apply imput force through rotary crank arms is limited by the rotary position thereof. Thus, the use of various elliptical or oval driving sprocket wheels has been suggested to variously apply the available input force to an annular driven rear axle sprocket wheel as disclosed in U.S. Pat. Nos. 596,289 of 1897, 885,982 of 1908, 2,693,119 of 1954, 2,827,797 of 1958, 3,259,398 of 1966, and 3,375,022 of 1968.
In addition to the presently commercially available basic single chain drive system, the concept of employing two separate drive systems which are each operable to rotate the one wheel of a bicycle during separate 180.degree. rotation of the crank arms has been known since at least as early as the Crane U.S. Pat. No. 258,559 of 1882. In such systems, each of the crankarms are connected to one of two drive sprocket means by cable or chain type driving means which are effective to transmit force to the wheel by movement from a radial innermost position to a radial outermost position relative to the wheel only during downward movement of an associated lever arm from an upper position to a lower position and are returned from the outermost position to the innermost position by use of one-way clutch means or the like during upward movement of the associated lever arm from the lower position to the upper position. Variations of such drive systems are disclosed in U.S. Pat. Nos. 258,559, 527,396, 598,246, 636,184, 849,342, 3,004,440, 3,375,023, 3,759,543, 3,834,733, 3,888,512 and 3,889,974. Such drive systems have utilized oscillatory type lever arms, reciprocatory type lever arms, and rotary type lever arms. In order to provide a range of variable speeds, various apparatus has been suggested including changing the pedal position relative to the lever arm (U.S. Pat. No. 258,559); changing the location of connection of the drive system on the lever arm (U.S. Pat. Nos. 527,396, 849,342, 3,375,023, 3,759,543 and 3,834,733), including multiplication of a selected speed (527,396); changing the location of an idler pulley or wheel member engaged with a chain intermediate the lever arm and the drive sprocket means (U.S. Pat. No. 636,184); changing the location of the pivotal axis of an intermediate pivotal link driven by the lever arms (U.S. Pat. No. 3,004,440); changing the fulcrum point of the lever arm (U.S. Pat. No. 3,888,512); and changing the radial location of application of force to a driven shaft intermediate the lever arm and the drive sprocket means (U.S. Pat. No. 3,889,974).
Thus the basic form of the drive systems of present day commercially available bicycles has been known for a long period of time. Essentially, all present day commercially available bicycle drive systems of which I am aware involve a force input means in the form of a driving sprocket wheel attached to a crank shaft driven by crank arms having pedals thereon with the force input sprocket wheel connected by a chain member to force output means in the form of a driven sprocket wheel mounted on and drivably connected to a rear wheel axle. Various drive system devices and apparatus have been proposed for providing varying mechanical advantage between the driving sprocket wheel and the driven sprocket wheel for the purpose of increasing or decreasing the speed of rotation of the rear wheel. Current conventional multiple speed (e.g., 3, 5 and 10 speed) bicycles utilize a drive system known as the derailleur system, which comprises a stack of varying diameter and varying tooth number output sprocket wheels. Such systems have many disadvantages, including cost, ease of maintenance and repair, reliability, limitations on available speed selection and shifting from one speed to another, and lack of adaptability to particular requirements of particular bike riding conditions and individual preferences and abilities of different bike riders.
Among the various objectives and advantages of the present invention are capability of selective correlation between available variable force input forces and desired force output characteristics; a drive system with much wider speed range capability and substantially infinite variable selection of speeds within a given speed range; capability of matching resistence to pedaling to the capability of separate groups of riders or individual riders; reduction of rider fatigue; substantially increasing effective output force for the same effective available input force; providing substantially wider effective gear range; a simple fast reaction shifting system with capability of shifting in less than one half pedal revolution at any time without significant loss of driving power; higher efficiency and reduced wear by use of straight line application of driving forces eliminating chain misalignment causing chain binding and sprocket wear associated with conventional systems; lower resistance drag during coasting; capability of fast easy wheel change and drive system part replacement; elimination of maintenance problems including periodic major adjustment requiring special procedures; elimination of need for a dished rear wheel; lower weight; fewer parts and less assembly time during manufacture and mounting on a bicycle.
In general, the inventive concepts are illustratively embodied herein in a bicycle drive system comprising rotatable crank shaft means; crank arm means operably connected to the crank shaft means to cause rotation thereof by application of input force; pedal means attached to the crank arm means for application of input force by a bike rider; cam means operably connected to and driven by the crank shaft means and the crank arm means for variously modifying the input force characteristics and transferring the available effective input force in accordance with predetermined desired characteristics; oscillator means operatively connected to and driven by the cam means for transferring the input force from the cam means as variously modified thereby; substantially infinitely variable speed change means associated with the oscillator means for selective variation of the speed of the bicycle throughout a relatively large range of speeds; rear wheel driving means operatively connected to and driven by the oscillator means and operatively connected to and driving the rear wheel of the bike for applying available force from the oscillator means to the rear wheel of the bicycle; and speed ratio changing means operatively associated with the rear wheel driving means for selective multiplication of the ratio of available bicycle speeds in the substantially infinitely variable range of speeds provided by the oscillator means for application by the rear wheel driving means to the rear wheel of the bicycle. It is to be understood that the various inventive concepts may be utilized by themselves or in sub-combinations or in other combinations to achieve various advantageous results for various other purposes. In addition, it is to be understood that some of the various inventive concepts are illustratively embodied herein in particular structure and in particular combinations providing particularly advantageous results.